Mushroom reduces grapefruit drug interactions

Grapefruit juice is off limits to people who take drugs like Zoloft (antidepressant), Carbatrol (anti-seizure), Lipitor (cholesterol control), Plendil (hypertension reduction), and Saquinavir (anti-HIV). The juice contains high levels of furanocoumarins, which inhibit enzymes that are necessary for metabolizing certain medications. This adverse drug interaction prevents many people from enjoying the taste and health benefits of grapefruit, which has been shown to protect against cancer and cardiovascular diseases.

Food chemists have employed numerous physical, biological, chemical, and microbiological methods to remove furanocoumarins from grapefruit juice with modest success. Out of all these techniques, one of the simplest involved using a fungus (Aspergillus niger) to soak up the furanocoumarins. However, that particular type of fungus is inedible. This led U.S. Department of Agriculture researchers, headed by Kyung Myung, to determine if edible varieties of fungi would work. Their research, which is published in the Journal of Agricultural and Food Chemistry, has identified four types of edible fungi that can reduce grapefruit-drug interactions.

Among the four fungi (Morchella esculenta, Monascus purpureus, Pleurotus sapidus, and Agaricus bisporus), M. esculenta was best at absorbing furanocoumarins. It removed nearly all of the furanocoumarins from grapefruit juice, leaving only a small amount of the most polar components. The M. esculenta treated juice showed a 40 percent decrease in its inhibition of the enzyme that is responsible for the undesirable drug interactions. The other three fungi were also able to eliminate furanocoumarins, with M. purpureus being the next best and A. bisporus being the least active.

Between the two major types of furanocoumarins (DHB and BM), all four fungi did better with BM, which is nonpolar. They were considerably less efficient at removing the polar DHB. This lead the authors to suggest that the chemical clearing power of fungi comes from the lipophilic components.

While the edible fungi are quite good at removing nonpolar furanocoumarins, the polar chemicals that remain still can hinder drug metabolizing enzymes. Nevertheless, a 40 percent decrease in enzyme interference is substantial. It just means that scientists must now focus on how to take care of the polar furanocoumarins that are left behind.

Yun Xie / Yun Xie / Yun Xie is a contributing science writer at Ars, where she covers the latest advancements in science and technology for Ars. She currently works in scientific communications, policy, and review.